we usually have them sharpened once a year in the spring, depends what kid of stuff you are cutting trough, if your just trimming bushes they will last a long time before needing to be done, if your guys are hacking through 1 inch thick stalks then they will need to be sharpened sooner or later.

We sharpen them at leat once a week but we do trim around 30-35 hours a week per trimmer. Sharp ones will leave a nicer finish, trim faster and i suppose it's better for the engine too. I also have to say we change the blades once every 2-3 monthsPosted via Mobile Device

We sharpen our stihl hedge trimmimers depending on the usage and the type of shrubs we trim. We don't overdue the sharpening because it wastes time and the blade doesn't last as long. We get new blades every Spring and go from there.